Processed allowing to provide the surface of metallic or glass substrates with various coatings are known, said coatings being e.g. useful for protecting metallic substrate from corrosion or for modifying surface properties of supports, for example for adjusting the wettability of a substrate (especially for enhancing the paintability).
In this connection a recurrent problem is the durability of the deposited coating.
Especially, phosphonic acids have been proposed for modifying surfaces, for example according to the method described in WO 2008/017721. In this connection, interesting coating layers based on gem-bisphosphonic compounds have been described as able to adsorb relatively strongly at surfaces and to form self assembled monolayers (SAMs). However, the durability of such layer is still limited by the interaction of the phosphonic group with the surface, which depends on the nature of the treated surface. Besides, the interactions are often not stable and may be reversed by hydrolysis under acidic or basic conditions or by washing with appropriate solvents. In many case, the stability of the interaction reveals unsufficient for ensuring an effective durability, especially on metals and inorganic surfaces such as glass.